The World Wide Web (WWW) has revolutionized the way people search for information. With increased affordability of computer and mobile devices, and improved network connectivity, the Internet has emerged as the preferred medium for people to find relevant and useful information. The emergence of a search engine has made this task a lot easier. A typical web search engine allows a user to provide one or more search terms through a browser based interface. It then searches the Web to retrieve a list of items related to the specified search terms. The retrieved items could be documents, images, videos, web links, etc.
Recognizing the continuous need of a user (and potentially billions of users), a number of companies have started offering web based search over the Internet. Google, Yahoo and Bing (from Microsoft) are some of the popular search engines that are around today. Increased competition amongst search service providers have resulted in various improvements over the algorithms behind the search engine technology. However, most of the search engines still concentrate on returning documents or web pages which are most relevant to the search key words. There are situations or user needs where these results may not be very helpful to an end user.